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Biomedical subjects

S Godfrey

Publications and source records attributed to S Godfrey.

At least 199 records · Page 11Linked to original sources
PubMed1978

Effect of practical timing of dosage on theophylline blood levels in asthmatic children treated with choline theophyllinate.

Two dosage schedules, 8 mg/kg per dose daily and 10 mg/kg per dose tds of choline theophyllinate were evaluated in asthmatic children. The times of the doses were considered the most practical for use outside hospital. Theophylline levels were measured 2 hours after each dose and were satisfactory in both schedules. The levels before the first dose of the day were, however, unsatisfactory. We emphasis the desirability of measuring blood levels in any patient receiving a theophylline compound.

Administration, Oral↗
PubMed1978

Cockayne's syndrome and emphysema.

A 5-year-old boy with Cockayne's syndrome is described. In addition to the recognised clinical features, he presented with severe fixed airways obstruction, and investigations confirmed clinical and physiological emphysema. In a disorder associated with many of the features of aging, it is probably that the presence of relative alpha-1-antitrypsin deficiency (1.5 g/l) in a child with PiMZ phenotype, contributed to his severe lung disease.

Airway Obstruction↗
PubMed1978

The refractory period after exercise-induced asthma: its duration and relation to the severity of exercise.

A study was carried out to determine whether an episode of exercise-induced asthma (EIA) is followed by a refractory period and to assess the factors that affect it. Nine children, 9 to 14 years of age, were studied during repeated, paired exercise tests on a treadmill. Respiratory function was assessed by measuring peak expiratory flow rate before and after exercise. Changes were related to measured uptake of O2 during exercise. When paired tests were at a constant metabolic load, the severity of EIA was relatively constant in the first test of each pair, but it diminished in the second tests as the interval between tests decreased. The ability to bronchoconstrict fully was recovered within 4 hours after a test. When tests at varying metabolic loads were followed after 30 min by tests at a constant load, the severity of EIA increased in proportion to the load in the first test of each pair. In the second tests it was inversely related to that which occurred in the first tests. These results were compatible with the suggestion that the development of EIA requires the release of a stored mediator or enzyme precursor.

Adolescent↗
PubMed1978

Airway resistance in infants after various treatments for hyaline membrane disease: special emphasis on prolonged high levels of inspired oxygen.

Thoracic gas volume, airway resistance (Raw), and dynamic lung compliance (CL) were measured in 48 infants surviving after hyaline membrane disease. Some infants were found to have a small reduction in CL after recovery from the acute phase of the illness but no other abnormalities were detected, irrespective of the type of treatment received. When studied again between the ages of 4 and 10 months, CL had returned to normal, but all infants who had been treated with intermittent positive pressure ventilation (IPPV) during the neonatal period were found to have developed a raised Raw. In contrast, all nonventilated infants, including those who had received up to five days of oxygen therapy in concentrations above 80%, had normal lung function. We conclude that IPPV, and not the increased inspired oxygen concentration, damaged the airways and interfered with their growth.

Airway Resistance↗
PubMed1977

Correlation between activation and dimer formation of rat renal phosphate-dependent glutaminase.

Gel filtration and velocity sedimentation in sucrose gradients were used to determine the molecular weights of purified rat renal phosphate-dependent glutaminase. The purified glutaminase has a molecular weight of 160,000 in Tris or barbital buffers and forms dimers of 332,000 molecular weight in the presence of its activator, Pi. The correlation between activation and dimer formation was investigated by determining the sedimentation coefficient at various concentrations of glutaminase activators. Saturation curves for Pi and riboflavin phosphate demonstrate an excellent correlation between per cent activation and increasing S20,w with increasing concentrations of these activators. The concentrations required for half-maximal saturation were 40 to 50 mM for Pi and 10 to 15 mM for riboflavin phosphate. Correlation between activation and dimer formation was also found with other activators at subsaturating concentrations. Moreover, the activation and dimer formation were found to be reversed to a similar extent by increasing concentrations of NaCl. Finally, we studied the effects of Pi and NaCl on the stability of glutaminase activity at 37 degrees. Pi stabilized glutaminase activity by increasing the t1/2 for inactivation from 12 min in the absence of Pi to 242 at 150 mM Pi. The concentration of Pi which gave approximately half-maximal change in t1/2 was 50 mM and addition of NaCl reversed this stabilization. These results support the hypothesis that phosphate-dependent glutaminase is active only as a dimer or larger aggregate. However, we cannot exclude the possibility that binding of Pi changes the monomer conformation sufficiently to produce activation and that this new conformation leads to self-association.

Animals↗
PubMed1977

Comparison of cromoglycate (cromolyn) and theophylline in controlling symptoms of chronic asthma. A collaborative study.

28 children with chronic asthma (15 in Denver and 13 in London) completed a 12 wk double-blind trial of treatment with sodium cromoglycate (cromolyn sodium), theophylline, and a combination of both. The three regimens were administered, each for 4 wk, in random sequence as part of a collaborative investigation of the relative efficacy of the two antiasthmatic agents. Cromoglycate was administered by inhalation in standard doses of 20 mg q.i.d. Theophylline dosage was individualized with the assistance of serum-theophylline measurements and averaged 6 mg/kg/dose q.i.d. (range 3-8--8-5 mg/kg/dose). Peak expiratory-flow rates measured twice daily on all patients averaged 75% of that predicted during cromoglycate administration, 79% during theophylline, and 81% during the combined-drug regimen (P less than 0.05). Patients had an average of 59% of days free of symptoms while on cromoglycate and 71% of days symptom-free when on both the theophylline and the combination regimens (P less than 0.025). None of the 13 patients whose asthmatic symptoms were previously controlled with cromoglycate was unable to complete the 4 wk trial with theophylline alone; 1 patient whose symptoms had been previously controlled with theophylline twice developed severe asthmatic symptoms while receiving cromoglycate, and he had to be withdrawn from that study period. No significant differences in adverse effects of the medication were observed during the 12 wk trial.

Adolescent↗
PubMed1977

A new method for investigating regional lung function in children with localized lung disease.

Lung function studies using 13Nitrogen have been used to determine regional and total lung function in 16 children suspected of having localized lung disease amenable to surgery. This method is simple, requires no active co-operation on the part of the child and gives a radiation dosage of about one-third of that for a bronchogram. The studies provided information about the severity and localization of the disease, and in addition, information about the remaining lung areas.

Asthma↗
PubMed1977

The place of radioisotopic lung function studies in paediatrics.

An analysis of the clinical value of radioisotopic lung function (RLF) tests has been carried out on the results of studies in 123 children with heart or lung disease. The overall incidence of useful RLF tests was 53%, but in children between 6 months and 6 years the incidence was higher (69%). The incidence of useful RLF test was similar whatever the question to be answered, although rather higher when information about differential pulmonary blood flow was required. Lists of conditions are presented for which the incidence of useful RLF tests is likely to be high (72%), moderate (46%), and low (14%).

Adolescent↗
PubMed1977

Hypertensive pulmonary vascular disease in children. Detection by radioactive nitrogen (13N) inhalation and injection.

Regional lung function has been studied in 16 children with intracardiac shunts and a variety of associated cardiac anomalies using radioactive nitrogen (13N) and a gamma camera-computer system. The distribution and washout of inhaled 13N were usually normal. The distribution of intravenously injected 13N was often abnormal and could be related to local anatomy. The most important finding was delayed clearance by ventilation of intravenously injected 13N in children with an abnormally raised pulmonary/systemic vascular resistance ratio (Rp/Rs) at cardiac catheterisation. The regional localisation of this ventilation-perfusion imbalance could be related in several children to the probable distribution of hypertensive pulmonary vascular disease, predicted either from local anatomy shown at cardiac catheterisation or from the abnormal distribution of pulmonary perfusion. Abnormalities present on breathing air may be partially reversed on breathing 100 per cent oxygen.

Child↗
PubMed1977

Specific airway conductance in relation to postconceptional age during infancy.

Thoracic gas volume (TGV) and airway conductance (Gaw) were measured in 69 healthy infants during the 1st yr of life, using an adaptation of the whole body plethysmographic technique in which a heated rebreathing system was used to eliminate temperature differences in respired gas. There was highly significant correlations between TGV and body wt (r=0.99), and between Gaw and TGV (r=0.97) in all the infants. However, the relationship between Gaw and TGV (i.e., specific conductance (SGaw)) was dependent on postconceptional age (PCA) in preterm infants, falling from 0.50 s-1-cmH2O-1 at 31 wk to 0.32 s-1-cmH2O-1 at 40 wk PCA. Gestational age and postnatal age per se did not affect this relationship, showing it to be a maturational event unaffected by the time of birth. After 40 wk, the decrease in SGaw was far more gradual throughout the 1st yr of life. Black and Chinese infants were found to have significantly higher values for SGaw than their White counterparts, which may be due to anatomical differences in nasal structure.

Airway Resistance↗
PubMed1977

A new apparatus for the accurate measurement of airway resistance in infancy.

A new heated rebreathing system has been developed for the measurement of thoracic gas volume (TGV) and airway resistance (Raw) in infants by the plethysmographic technique. The apparatus has a linear response to flow rates between 0-160 ml-s-1, a dead space of 12 ml and a resistance of 5 cmH2O-1-1-S-1 at a flow rate of 60 ml-s-1. The inclusion of pneumatically operated valves in the apparatus is a major improvement over previous methods of occlusion for TGV measurements. The infant is allowed to rebreathe saturated gas at body temperature through the heated system, thus overcoming a potential source of error when measuring Raw in infants. Using this apparatus, the average coefficient of variation was 3.7% for TGV and 5.9% for Raw.

Airway Resistance↗
PubMed1977

Measurement of pulmonary capillary blood flow in infants by plethysmography.

An accurate method for measuring effective pulmonary capillary blood flow (Qc eff) in infants has been developed with an adaptation of the plethysmographic technique. Measurements were made on 19 preterm. 14 small-for-dates, and 7 fullterm normal infants with a constant volume whole body plethysmograph in which the infant rebreathed nitrous oxide. There was a highly significant correlation between Qc eff and body weight, and this relationship was unaffected by premature delivery or intrauterine growth retardation. Mean Qc eff in preterm, small-for dates, and fullterm infants was 203, 208 and 197 ml min-1 kg-1, respectively, with no significant differences between the groups. A significant negative correlation existed between Qc eff and haematocrit in the preterm infants. There was no relationship between weight standardized Qc eff and postnatal age in any of the groups. With this technique, it was possible to readily recognise the presence of rapid recirculation (indicative of shunting) in several of the infants, suggesting that rebreathing methods for the assessment of Qc eff should not be applied indiscriminately during the neonatal period. By taking care to overcome the potential sources of technical error, it was possible to obtain highly reproducible results of Qc eff in infants over a wider age range than has been previously reported.

Body Weight↗